Microstructure And Properties Of SiC_p/Al-Si Composites For Electronic Packaging

Focused on the problems of poor wettability and susceptible to interfacial reaction between Al and SiC existed in SiCp/Al composites, SiCp/Al and SiCp/Al-Si composites were prepared with hot pressing sintering technique in this study, through surface modification pretreatment of SiC particles and adding Si to Al matrix. Surface modification pretreatment of SiC particles and reaction thermodynamics between Al and SiC were studied systematically. The influence of different preparation methods on organization and performance of the composite was also investigated. Structural analysis, physical properties and mechanical properties measurement of the composites prepared in different process parameters which contained different Si contents, were carried out. The main results achieved were summarized as follows:After surface modification pretreatment, the angular of SiC particles became passivated, the shape of particles became close to spherical and the specific surface area of particles decreased. At the same time, the surface microscopic features of SiC particles changed, which strengthened interface bonding and improved thermal conductivity of the composites. It’s shown by DSC kinetic results that thermodynamic chemical reaction between Al and SiC couldn’t easily happen when the temperature was held nearby the melting of Al for a short time, and the parameters of fabrication process were optimized. By selecting appropriate process parameters, composite fabricated by hot pressing sintering technique was expected to get excellent overall performance.The SiCp/Al composites sintered at650℃for20min under pressure of30MPa, in which10wt%Si were added into Al matrix, were prepared by hot pressing sintering technique. The results showed that the SiC particles distributed uniformly in the composite matrix, and overall composite was dense. The TEM structure observation showed that the clean interface between the reinforcement and the matrix was gained without any transient layer and other reactants, and the interface bonding was well. The orientation relationship between Al and SiC was also decided.The physical propertities and mechanical properties of SiCp/Al-Si composites were increased greatly through the optimization research of the preparation process parameters, organization and performance. Especially, the thermal conductivity of the composites were significantly improved, solving the problem of low thermal conductivity of SiCp/Al composite due to poor wettability between Al and SiC. When adding10wt%Si to Al matrix and the paticle size of SiC was30μm, the composite sintered at650℃under pressure of30MPa had excellent properties. The thermal conductivity can reach as high as189W.m-1.K-1, the average coefficient of thermal expansion between50-400℃was9.5×10-6/℃and the bending strength was up to300MPa. All these three parameters can meet the requirements of electronic packaging materials.